wasmtime_wasi_http/
lib.rs

1//! Wasmtime's implementation of `wasi:http`
2//!
3//! This crate is organized similarly to [`wasmtime_wasi`] where there is a
4//! top-level [`p2`] and [`p3`] module corresponding to the implementation for
5//! WASIp2 and WASIp3.
6
7#![deny(missing_docs)]
8#![doc(test(attr(deny(warnings))))]
9#![doc(test(attr(allow(dead_code, unused_variables, unused_mut))))]
10#![cfg_attr(docsrs, feature(doc_cfg))]
11
12use http::{HeaderName, header};
13
14mod ctx;
15mod field_map;
16#[cfg(feature = "component-model-async")]
17pub mod handler;
18pub mod io;
19#[cfg(feature = "p2")]
20pub mod p2;
21#[cfg(feature = "p3")]
22pub mod p3;
23
24pub use ctx::*;
25pub use field_map::*;
26
27/// Extract the `Content-Length` header value from a [`http::HeaderMap`], returning `None` if it's not
28/// present. This function will return `Err` if it's not possible to parse the `Content-Length`
29/// header.
30#[cfg(any(feature = "p2", feature = "p3"))]
31fn get_content_length(headers: &http::HeaderMap) -> wasmtime::Result<Option<u64>> {
32    let Some(v) = headers.get(header::CONTENT_LENGTH) else {
33        return Ok(None);
34    };
35    let v = v.to_str()?;
36    // RFC 9110 defines `Content-Length` as `1*DIGIT`. `u64`'s `FromStr` is more
37    // lenient and also accepts a leading `+`, so reject anything that isn't a
38    // non-empty run of decimal digits before parsing.
39    if v.is_empty() || !v.bytes().all(|b| b.is_ascii_digit()) {
40        wasmtime::bail!("invalid `content-length` header value: {v:?}");
41    }
42    let v = v.parse()?;
43    Ok(Some(v))
44}
45
46#[cfg(all(test, any(feature = "p2", feature = "p3")))]
47mod content_length_tests {
48    use super::get_content_length;
49    use http::{HeaderMap, HeaderValue, header};
50
51    fn headers(value: &str) -> HeaderMap {
52        let mut map = HeaderMap::new();
53        map.insert(
54            header::CONTENT_LENGTH,
55            HeaderValue::from_str(value).unwrap(),
56        );
57        map
58    }
59
60    #[test]
61    fn content_length_must_be_decimal_digits() {
62        assert_eq!(get_content_length(&HeaderMap::new()).unwrap(), None);
63        assert_eq!(get_content_length(&headers("0")).unwrap(), Some(0));
64        assert_eq!(get_content_length(&headers("1234")).unwrap(), Some(1234));
65
66        // `u64::from_str` accepts these but they are not `1*DIGIT` per RFC 9110.
67        assert!(get_content_length(&headers("+5")).is_err());
68        assert!(get_content_length(&headers("-5")).is_err());
69        assert!(get_content_length(&headers(" 5")).is_err());
70        assert!(get_content_length(&headers("")).is_err());
71    }
72}
73
74/// Set of [http::header::HeaderName], that are forbidden by default
75/// for requests and responses originating in the guest.
76pub const DEFAULT_FORBIDDEN_HEADERS: [HeaderName; 9] = [
77    header::CONNECTION,
78    HeaderName::from_static("keep-alive"),
79    header::PROXY_AUTHENTICATE,
80    header::PROXY_AUTHORIZATION,
81    HeaderName::from_static("proxy-connection"),
82    header::TRANSFER_ENCODING,
83    header::UPGRADE,
84    header::HOST,
85    HeaderName::from_static("http2-settings"),
86];
wasmtime_wasi_http/lib.rs

wasmtime_wasi_http/
lib.rs
